Bonded structure employing metal semiconductor alloy bonding

ABSTRACT

Vertical stacks of a metal portion and a semiconductor portion formed on a first substrate are brought into physical contact with vertical stacks of a metal portion and a semiconductor portion formed on a second substrate. Alternately, vertical stacks of a metal portion and a semiconductor portion formed on a first substrate are brought into physical contact with metal portions formed on a second substrate. The assembly of the first and second substrates is subjected to an anneal at a temperature that induces formation of a metal semiconductor alloy derived from the semiconductor portions and the metal portions. The first substrate and the second substrate are bonded through metal semiconductor alloy portions that adhere to the first and second substrates.

BACKGROUND

This invention relates to a bonded structure that provides bondingbetween multiple substrates through formation of a metal semiconductoralloy and methods of manufacturing the same.

Bonding of multiple substrates is required to enable three-dimensionalintegration of chips. Bonding of two substrates can be achieved byadhesion of two dielectric materials as in an oxide-to-oxide bondingthat fuses silicon dioxide materials from two substrates after bonding,by adhesion between two metallic material as in a copper-to-copperbonding that employs direct contact between opposing copper pads and asubsequent grain growth across the original interface between theopposing copper pads, or by a method employing a combination of the twoadhesion mechanisms.

Through-substrate-via (TSV) structures, formed after multiple substratesare bonded and optionally thinned, provide electrical connection acrossthe multiple substrates in a bonded structure. A TSV structure mayinclude a conductive material such as copper, which diffuses rapidly inthe plane of the bonding interface between substrates becausemicroscopic irregularities and cavities are present at the interface.Diffusion of the conductive material from a TSV structure into thesurrounding substrate region can cause electrical shorts and reliabilityproblems in the bonded structure.

An interfacial layer, such as silicon nitride, can be employed to reducesubsequent diffusion of conductive material from TSV structures. In thiscase, the diffusion resistant materials retard lateral diffusion of theconductive material from the TSV structures along the interface betweentwo bonded substrates, thereby preventing electrical shorts.

Diffusion of materials across the original interface provides theadhesion strength between two bonded substrates in prior art bondingmethods. Because the diffusion of materials across a bonding interfaceis thermally driven and the temperature of the anneal is limited forsemiconductor substrates to a temperature range that does not causedecomposition of back-end-of-line (BEOL) dielectric materials, thebonding strength provided by conventional methods of substrate bondingcan be limited.

BRIEF SUMMARY

Vertical stacks of a metal portion and a semiconductor portion formed ona first substrate are brought into physical contact with vertical stacksof a metal portion and a semiconductor portion formed on a secondsubstrate. Alternately, vertical stacks of a metal portion and asemiconductor portion formed on a first substrate are brought intophysical contact with metal portions formed on a second substrate. Theassembly of the first and second substrates is subjected to an anneal ata temperature that induces formation of a metal semiconductor alloyderived from the semiconductor portions and the metal portions. Thefirst substrate and the second substrate are bonded through metalsemiconductor alloy portions that adhere to the first and secondsubstrates. Electrically conductive paths can be formed across the firstand second substrates through conductive structures that contact themetal semiconductor alloy portions or by through-substrate vias that aresubsequently formed in the bonded structure.

According to an aspect of the present invention, a bonded structure isprovided, which includes a vertical stack of a first substrate and asecond substrate. The first substrate includes first dielectric materialportions and the second substrate includes second dielectric materialportions. Each of the second dielectric material portions contacts asurface of one of the first dielectric material portions at an interfaceplane between the first and second substrates. The first dielectricmaterial portions and the second dielectric material portions laterallycontact metal semiconductor alloy portions. Each of the metalsemiconductor alloy portions extends across the interface into the firstsubstrate and the second substrate.

According to another aspect of the present invention, a method offorming a bonded structure is provided, which includes forming firstdielectric material portions on a surface of a first substrate; formingmaterial stacks of a first metal portion and a first semiconductorportion on the first substrate; forming second dielectric materialportions on a surface of a second substrate; forming metal-containingmaterial portions including at least a second metal portion on thesecond substrate; and bringing the material stacks and themetal-containing material portions into physical contact at an interfaceplane and annealing the first and second substrates, whereby metalsemiconductor alloy portions are formed across the interface plane byconversion of materials of the material stacks and the metal-containingmaterial portions into a metal semiconductor alloy.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIGS. 1-5 are sequential vertical cross-sectional views of a firstexemplary structure according to a first embodiment of the presentinvention.

FIGS. 6-8 are sequential vertical cross-sectional views of a secondexemplary structure according to a second embodiment of the presentinvention.

FIGS. 9 and 10 are sequential vertical cross-sectional views of a thirdexemplary structure according to a third embodiment of the presentinvention.

FIGS. 11-13 are sequential vertical cross-sectional views of a fourthexemplary structure according to a fourth embodiment of the presentinvention.

FIG. 14 is a vertical cross-sectional view of a fifth exemplarystructure according to a fifth embodiment of the present invention.

FIG. 15 is a vertical cross-sectional view of a sixth exemplarystructure according to a sixth embodiment of the present invention.

FIG. 16 is a vertical cross-sectional view of a seventh exemplarystructure according to a seventh embodiment of the present invention.

FIGS. 17-19 are sequential vertical cross-sectional views of an eighthexemplary structure according to an eighth embodiment of the presentinvention.

DETAILED DESCRIPTION

As stated above, the present invention relates to a bonded structurethat provides bonding between multiple substrates through formation of ametal semiconductor alloy and methods of manufacturing the same, whichare now described in detail with accompanying figures. It is noted thatlike reference numerals refer to like elements across differentembodiments. The drawings are not necessarily drawn to scale.

As used herein, a “metal” refers to any elemental metal in the PeriodicTable of Elements.

As used herein, a “non-metal” refers to any element that is not anelemental metal in the Periodic Table of Elements.

As used herein, a “metallic material” is a material including at leastone elemental metal. A metallic material may consist of an elementalmetal, an intermetallic alloy of at least two elemental metals, or analloy of at least one elemental metal and at least one non-metallicelement.

As used herein, an “intermetallic alloy” is an alloy consisting of atleast two elemental metals.

As used herein, a “metallic alloy” is a conductive alloy including atleast one elemental metal and at least another element.

As used herein, a “conductive line structure” refers to a conductivestructure that extends in a direction within a plane that is parallel toa surface of a substrate on which the conductive line structure islocated.

As used herein, a “conductive via structure” refers to a conductivestructure that extends in a direction that is nominally perpendicular toa plane that is parallel to a surface of a substrate on which theconductive via structure is located.

As used herein, a “conductive wiring structures” include conductive linestructures that provide electrical connection within a plane andconductive via structures that provide electrical connection in adirection nominally perpendicular to said plane.

As used herein, a “metal-containing material portion” is a portion of amaterial that includes at least one elemental metal.

As used herein, “transition metals” include elements in Groups IVB, VB,VIB, VIIB, VIIIB, IB, and IIB other than Actinides and Lanthanides.

As used herein, “Lanthanides” includes element having an atomic numberfrom 57 to 71.

As used herein, “Actinides” includes elements having an atomic numberfrom 89 to 103.

Referring to FIG. 1, a first exemplary structure according to a firstembodiment of the present invention includes a first substrate 100 and asecond substrate 200 that are separated from each other. The firstsubstrate 100 can include a first semiconductor substrate 101 and afirst interconnect-level structure 151. The second substrate 200 caninclude a second semiconductor substrate 201 and a secondinterconnect-level structure 251.

The first semiconductor substrate 101 includes a first semiconductorlayer 110. At least one first semiconductor device 120 can be present onthe first semiconductor layer 110.

Likewise, the second semiconductor substrate 201 includes a secondsemiconductor layer 210. At least one second semiconductor device 220can be present on the second semiconductor layer 210. Each of the atleast one first semiconductor device 120 and the at least one secondsemiconductor device 220 can be, but is not limited to, a field effecttransistor, a bipolar transistor, a diode, a resistor, a capacitor, avaractor, an inductor, a carbon nanotube device, or any other type ofsemiconductor device or a nanoscale device. As an illustrative example,field effect transistors are depicted as the at least one firstsemiconductor device 120 and the at least one second semiconductordevice 220 in FIG. 1. A buried insulator layer (not shown) and/or ahandle substrate (not shown) can be present within the firstsemiconductor layer 110 and/or the second semiconductor layer 210.

Each of the first semiconductor layer 110 and the second semiconductorlayer 210 includes a semiconductor material. Preferably, thesemiconductor material can be a single crystalline semiconductormaterial having an epitaxial alignment among atoms within the entiretyof the top semiconductor layer. The semiconductor material may beselected from, but is not limited to, silicon, germanium,silicon-germanium alloy, silicon carbon alloy, silicon-germanium-carbonalloy, gallium arsenide, indium arsenide, indium phosphide, III-Vcompound semiconductor materials, II-VI compound semiconductormaterials, organic semiconductor materials, and other compoundsemiconductor materials. For example, the semiconductor material maycomprise single crystalline silicon.

The first interconnect level structure 151 includes at least one firstdielectric material layer 140 and first conductive wiring structures 150embedded therein. The first conductive wiring structures 150 can includefirst conductive via structures 152 and first conductive line structures154. The second interconnect level structure 251 includes at least onesecond dielectric material layer 240 and second conductive wiringstructures 250 embedded therein. The second conductive wiring structures250 can include second conductive via structures 252 and secondconductive line structures 254.

Each of the at least one first dielectric material layer 140 and the atleast one second dielectric material layer 240 includes at least onedielectric material, which can be a doped or undoped silicate glass,silicon nitride, a low dielectric constant (low-k) chemical vapordeposition (CVD) material such as organosilicate glass, a low-k spin-ondielectric material such as SiLK™, BLoK™, NBLoK™, or any other type ofdielectric material that can be deposited or formed on a substrate andable to hold at least one metal pad therein. The first conductive wiringstructures 150 embedded in the at least one first dielectric materiallayer 140 provide electrical connection to the at least one firstsemiconductor device 120. Likewise, second conductive wiring structures250 embedded in the at least one second dielectric material layer 214provide electrical connection to the at least one second semiconductordevice 220.

Each of the at least one first dielectric material layer 140 and the atleast one second dielectric material layer 240 can include a pluralityof dielectric material layers having different compositions. Thecomposition of the at least one first dielectric material layer 140 andthe at least one second dielectric material layer 240 can include anydielectric material known in semiconductor processing technology and canbe adjusted as needed.

A first planar dielectric layer 160 can be optionally formed on the topsurface of the first interconnect level structure 151. The first planardielectric layer 160 can be deposited on a planar top surface of thefirst interconnect level structure 151. Likewise, a second planardielectric layer 260 can be optionally formed on the top surface of thesecond interconnect level structure 251. The second planar dielectriclayer 260 can be deposited on a planar top surface of the secondinterconnect level structure 251. Each of the first planar dielectriclayer 160 and the second planar dielectric layer includes a dielectricmaterial such as silicon oxide, silicon nitride, silicon oxynitride,organosilicate glass (OSG), or any other dielectric material that can beemployed for the at least one first dielectric material layer 140 or theat least one second dielectric material layer 240. The thickness of thefirst planar dielectric layer 160 and the thickness of the second planardielectric layer 260 can be from 10 nm to 1,000 nm, although lesser andgreater thicknesses can also be employed.

A stack of a first metal layer 170L and a first semiconductor layer 180Lis deposited. The first metal layer 170L is deposited on the exposed topsurface of the first substrate 100, which can be the surface of thefirst interconnect level structure 151 or the surface of the firstplanar dielectric layer 160. The first semiconductor layer 180L isdeposited on the surface of the first metal layer 170L. Each of thefirst metal layer 170L and the first semiconductor layer 180L isdeposited as a contiguous blanket layer. Upon deposition, the stack ofthe first metal layer 170L and the first semiconductor layer 180L isincorporated into the first substrate 100.

Likewise, a stack of a second metal layer 270L and a secondsemiconductor layer 280L is deposited. The second metal layer 270L isdeposited on the exposed top surface of the second substrate 200, whichcan be the surface of the second interconnect level structure 251 or thesurface of the second planar dielectric layer 260. The secondsemiconductor layer 280L is deposited on the surface of the second metallayer 270L. Each of the second metal layer 270L and the secondsemiconductor layer 280L is deposited as a contiguous blanket layer.Upon deposition, the stack of the second metal layer 270L and the secondsemiconductor layer 280L is incorporated into the second substrate 200.

Each of the first metal layer 170L and the second metal layer 270Lincludes at least one metal selected from transition metals,Lanthanides, and Actinides. Each of the first metal layer 170L and thesecond metal layer 270L can be composed of a single elemental metalselected from transition metals, Lanthanides, and Actinides, or can becomposed of an intermetallic alloy of at least two elements selectedfrom transition metals, Lanthanides, and Actinides.

Preferably, each of the first metal layer 170L and the second metallayer 270L includes at least 30% Ni in atomic percentage. Morepreferably, each of the first metal layer 170L and the second metallayer 270L includes at least 50% Ni in atomic percentage. Each of thefirst metal layer 170L and the second metal layer 270L can consist ofNi, or can be composed of an intermetallic alloy including Ni at anatomic concentration of at least 30%, or preferably at an atomicconcentration of at least 50%.

Each of the first metal layer 170L and the second metal layer 270L canbe deposited by physical vapor deposition (PVD), chemical vapordeposition (CVD), evaporation, electroless plating, electroplating, or acombination thereof. The thickness of the first metal layer 170L and thethickness of the second metal layer 270L can be independently from 5 nmto 300 nm, and typically from 15 nm to 100 nm, although lesser andgreater thicknesses can also be employed.

Each of the first semiconductor layer 180L and the second semiconductorlayer 280L includes at least one semiconductor material selected fromsilicon, germanium, silicon-germanium alloy, silicon carbon alloy,silicon-germanium-carbon alloy, gallium arsenide, indium arsenide,indium phosphide, III-V compound semiconductor materials, II-VI compoundsemiconductor materials, organic semiconductor materials, and othercompound semiconductor materials. Preferably, each of the firstsemiconductor layer 180L and the second semiconductor layer 280Lincludes at least one element selected from Si and Ge. For example, eachof the first semiconductor layer 180L and the second semiconductor layer280L can be composed of a semiconductor material selected from silicon,germanium, a silicon-germanium alloy, a silicon-carbon alloy, agermanium-carbon alloy, or a silicon-germanium-carbon alloy.

Each of the first semiconductor layer 180L and the second semiconductorlayer 280L can be deposited by plasma enhanced chemical vapor deposition(PECVD), low pressure chemical vapor deposition (LPCVD), physical vapordeposition (PVD), or a combination thereof. The thickness of the firstsemiconductor layer 180L and the thickness of the second semiconductorlayer 280L can be independently from 5 nm to 100 nm, and typically from10 nm to 30 nm, although lesser and greater thicknesses can also beemployed.

Referring to FIG. 2, the stack of the first metal layer 170L and thefirst semiconductor layer 180L is patterned to form trenches therein.The stack of the first metal layer 170L and the first semiconductorlayer 180L can be patterned, for example, by a combination oflithographic methods that forms a patterned photoresist and an etch thattransfers the pattern in the openings of the patterned photoresist intothe stack of the first metal layer 170L and the first semiconductorlayer 180L. A top surface of the first planar dielectric layer 160 isexposed at the bottom of each trench in the stack of the first metallayer 170L and the first semiconductor layer 180L. The remainingportions of the first metal layer 170L and the first semiconductor layer180L form first metal-containing material portions, each of which is afirst material stack of a first metal portion 170 and a firstsemiconductor portion 180. Each first metal-containing material portioncan be laterally spaced by the trenches on the first substrate 100.

Similarly, the stack of the second metal layer 270L and the secondsemiconductor layer 280L is patterned to form trenches therein. A topsurface of the second planar dielectric layer 260 is exposed at thebottom of each trench in the stack of the second metal layer 270L andthe second semiconductor layer 280L. Preferably, the pattern of trenchesin the stack of the first metal layer 170L and the first semiconductorlayer 180L is a mirror image of the pattern of trenches in the stack ofthe second metal layer 270L and the second semiconductor layer 280L. Theremaining portions of the second metal layer 270L and the secondsemiconductor layer 280L form second metal-containing material portions,each of which is a second material stack of a second metal portion 270and a second semiconductor portion 280. Each second metal-containingmaterial portion can be laterally spaced by the trenches on the secondsubstrate 200.

A first dielectric material is deposited in the trenches among remainingportions of the first metal layer 170L and the first semiconductor layer180L, and is planarized to form first dielectric material portions 190.The first dielectric material above the top surface of the firstsemiconductor layer 180L is removed during a planarization step so thatremaining portions of the first semiconductor layer 180 is exposed afterthe planarization step. The top surfaces of the first semiconductorportions 180 and the top surfaces of the first dielectric materialportions 190 can be coplanar. The first metal-containing materialportions (170, 180) and the first dielectric material portions 190complimentarily fill the entirety of the layer between the top surfaceof the first planar dielectric layer 160 and the plane of the topsurfaces of the first semiconductor portions 180 and the firstdielectric material portions 190.

Likewise, a second dielectric material is deposited in the trenchesamong remaining portions of the second metal layer 270L and the secondsemiconductor layer 280L, and is planarized to form second dielectricmaterial portions 290. The second dielectric material above the topsurface of the second semiconductor portions 280 is removed during aplanarization step so that remaining portions of the secondsemiconductor layer 280 is exposed after the planarization step. The topsurfaces of the second semiconductor portions 280 and the top surfacesof the second dielectric material portions 290 can be coplanar. Thesecond metal-containing material portions (270, 280) and the seconddielectric material portions 290 complimentarily fill the entirety ofthe layer between the top surface of the second planar dielectric layer260 and the plane of the top surfaces of the second semiconductorportions 280 and the second dielectric material portions 290.

Referring to FIG. 3, the second substrate 200 is flipped upside down.Subsequently, the first substrate 100 and the second substrate 200 arebrought into physical contact with each other. Preferably, the firstmetal-containing material portions (170, 180) and the secondmetal-containing material portions (270, 280) are brought into contactwith each other so that a surface of each second semiconductor portion280 contacts a surface of one of the first semiconductor portions 180 atan interface plane. Preferably, a surface of each of the firstsemiconductor portions 180 contacts a surface of one of the secondsemiconductor portions 280 when the first metal-containing materialportions (170, 180) and the second metal-containing material portions(270, 280) are brought into contact with each other. The interface planeis the plane of the top surfaces of the first semiconductor portions 180and first dielectric material portions 190 as well as the plane of thetop surfaces (now located at the bottommost portion of the secondsubstrate 200 after flipping upside down) of the second semiconductorportions 280 and the second dielectric material portions 290.

Referring to FIG. 4, metal semiconductor alloy portions 300 are formedacross the interface plane by conversion of materials of the firstmetal-containing material portions (170, 180) and the secondmetal-containing material portions (270, 280) into a metal semiconductoralloy. The conversion can be effected by an anneal process, which can beperformed, for example, at a temperature from 300° C. to 500° C. Abonded structure including a vertical stack of the first substrate 100and the second substrate 200 is thereby formed. Each of the seconddielectric material portions 290 contacts a surface of one of the firstdielectric material portions 190 at an interface plane between the firstand second substrates (100, 200). The first dielectric material portions190 and the second dielectric material portions 290 laterally surroundmetal semiconductor alloy portions 300. Each of the metal semiconductoralloy portions 300 extends across the interface into the first substrate100 and the second substrate 200. The metal semiconductor alloy portions300 provides adhesive force to the first substrate 100 and the secondsubstrate 200, thereby providing bonding between the first and secondsubstrates (100, 200). Further, the contact between the first and seconddielectric material portions (190, 290) can induce diffusion ofmaterials across the interface plane to provide additional adhesiveforce in some cases.

The materials of the first semiconductor portions 180 and the secondsemiconductor portions 280 diffuse across the interface plane during theformation of the metal semiconductor alloy. Further, the materials ofthe first metal portions 170 and the second metal portions 270 can alsodiffuse toward the interface plane during the formation of the metalsemiconductor alloy. In one case, the entirety of each metalsemiconductor alloy portion 300 is a homogeneous metal semiconductoralloy. In another case, a metal semiconductor alloy portion 300 can havea heterogeneous composition in which a metal semiconductor alloy ispresent around the interface plane and a metal or a metallic alloy ispresent in at least one end portion of the metal semiconductor alloyportion 300. If present, the metal or the metal alloy contacts one ofthe first and second planar dielectric layers (160, 260) or one of thefirst and interconnect level structures (151, 251).

Each metal semiconductor alloy portion 300 includes an alloy of at leastone metal and at least one semiconductor material. The at least onemetal is derived from the first metal portions 170 and the second metalportions 270 (See FIG. 3). Thus, the at least one metal is selected fromtransition metals, Lanthanides, and Actinides. Further, the at least onesemiconductor material is derived from the first semiconductor portions180 and the second semiconductor portions 280. (See FIG. 3). Thus, theat least one semiconductor material is selected from silicon, germanium,silicon-germanium alloy, silicon carbon alloy, silicon-germanium-carbonalloy, gallium arsenide, indium arsenide, indium phosphide, III-Vcompound semiconductor materials, II-VI compound semiconductormaterials, organic semiconductor materials, and other compoundsemiconductor materials. Preferably, the at least one semiconductormaterial includes at least one element selected from Si and Ge. In thiscase, the metal semiconductor alloy portions 300 include a metalsilicide, a metal germanide, or a metal germanosilicide.

If nickel is included in the first metal portions 170 or the secondmetal portions 270, the metal semiconductor alloy portions 300 includeNi. Preferably, the metal semiconductor alloy portions 300 include anickel silicide, a nickel germanide, or a nickel germanosilicide. Themetal semiconductor alloy portions 300 can be composed of a nickelsilicide, a nickel germanide, or a nickel germanosilicide. Alternately,the metal semiconductor alloy portions 300 can include an alloy of anickel silicide and a silicide of at least another metal, an alloy of anickel germanide and a germanide of at least another metal, or an alloyof a nickel germanosilicide and a germanosilicide of at least anothermetal.

The first interconnect-level structure 151 is more proximal to theinterface plane than the first semiconductor substrate 101, and thesecond interconnect-level structure 251 is more proximal to theinterface than the second semiconductor substrate 201. The first planardielectric layer 160, if present, is located between the at least onefirst semiconductor device 120 and the interface plane and contacts thefirst dielectric material portions 190 and one end of each of the metalsemiconductor alloy portions 300. The second planar dielectric layer260, if present, is located between the at least one secondsemiconductor device 220 and the interface plane and contacts the seconddielectric material portions 290 and another end of the metalsemiconductor alloy portions 300.

Referring to FIG. 5, at least two through-substrate via structures 310that extend through the second substrate 200 are formed by methods knownin the art. Dielectric liners (not shown) can be formed around each ofthe at least two through-substrate via structures 310 to electricallyisolate the at least two through-substrate via structures 310 from thesecond semiconductor substrate 201 and the at least one seconddielectric material layer 240. A through-substrate via structure 310 cancontact one of the second conductive wiring structures 250 or one of thefirst conductive wiring structures 150. If a through-substrate viastructure 310 contacts one of the first conductive wiring structures150, the through-substrate via structure 310 can pass through a stack ofa first dielectric material portion 190 and a second dielectric materialportion 290, or through a metal semiconductor alloy portion 300.

At least one metal line 320 can be formed on the outer surface of thesecond substrate 200, i.e., the exposed surface of the secondsemiconductor substrate 201, by method known in the art. The at leastone metal line 320 contacts the at least two through-substrate viastructures 310 to provide at least one conductive electrical connectionbetween the at least one first semiconductor devices 120 and the atleast one second semiconductor devices 220.

Referring to FIG. 6, a second exemplary structure according to a secondembodiment of the present invention can be provided by modifying theprocess of forming the first exemplary structure of FIG. 1.Specifically, instead of forming a first metal layer 170L and a secondmetal layer 180L (See FIG. 1), a first dielectric material portions 190is formed on the first substrate 100. The first dielectric materialportions 190 can be formed, for example, by depositing a firstdielectric material layer (not shown) on a surface of the firstsubstrate 100 as a contiguous blanket layer, and by patterning the firstdielectric material layer to form trenches therein. The first dielectricmaterial portions 190 are formed on the first substrate 100, and thefirst dielectric material portions 190 are laterally spaced by thetrenches.

Likewise, instead of forming a second metal layer 270L and a secondmetal layer 280L (See FIG. 1), a second dielectric material portions 290is formed on the second substrate 200. The second dielectric materialportions 290 can be formed, for example, by depositing a seconddielectric material layer (not shown) on a surface of the secondsubstrate 200 as a contiguous blanket layer, and by patterning thesecond dielectric material layer to form trenches therein. The seconddielectric material portions 290 are formed on the second substrate 200,and the second dielectric material portions 290 are laterally spaced bythe trenches.

Referring to FIG. 7, a stack of a first metal layer 170L and a firstsemiconductor layer 180L is deposited over the first dielectric materialportions 190 and in the trenches on the first substrate 100. Surfaces ofthe first metal layer 170L and the first semiconductor layer 180Lreplicate the underlying topography generated by the first dielectricmaterial portions 190. The composition and thickness of each of thefirst metal layer 170L and the first semiconductor layer 180L can be thesame as in the first embodiment.

Likewise, a stack of a second metal layer 270L and a secondsemiconductor layer 280L is deposited over the second dielectricmaterial portions 290 and in the trenches on the second substrate 200.Surfaces of the second metal layer 270L and the second semiconductorlayer 280L replicate the underlying topography generated by the seconddielectric material portions 290. The composition and thickness of eachof the second metal layer 270L and the second semiconductor layer 280Lcan be the same as in the first embodiment.

Referring to FIG. 8, the portions of the stack of a first metal layer170L and the first semiconductor layer 180L above the first dielectricmaterial portions 190 is planarized. Top surfaces of the firstdielectric material portions 190 can be employed as a stopping layer.The remaining portions of the first metal layer 170L and the firstsemiconductor layer 180L constitute first metal-containing materialportions, each of which is a first material stack of a first metalportion 170 and a first semiconductor portion 180. Each firstmetal-containing material portion can be laterally spaced by the firstdielectric material portions 190 on the first substrate 100. Each firstsemiconductor portion 180 is spaced from the first dielectric materialportions 190 by at least one first metal portion 170. The firstmetal-containing material portions (170, 180) and the first dielectricmaterial portions 190 complimentarily fill the entirety of the layerbetween the top surface of the first planar dielectric layer 160 and theplane of the top surfaces of the first semiconductor portions 180 andthe first dielectric material portions 190.

Likewise, the portions of the stack of a second metal layer 270L and thesecond semiconductor layer 280L above the second dielectric materialportions 290 is planarized. Top surfaces of the second dielectricmaterial portions 290 can be employed as a stopping layer. The remainingportions of the second metal layer 270L and the second semiconductorlayer 280L constitute second metal-containing material portions, each ofwhich is a second material stack of a second metal portion 270 and asecond semiconductor portion 280. Each second metal-containing materialportion can be laterally spaced by the second dielectric materialportions 290 on the second substrate 200. Each second semiconductorportion 280 is spaced from the second dielectric material portions 290by at least one second metal portion 270. The second metal-containingmaterial portions (270, 280) and the second dielectric material portions290 complimentarily fill the entirety of the layer between the topsurface of the second planar dielectric layer 260 and the plane of thetop surfaces of the second semiconductor portions 280 and the seconddielectric material portions 290.

The second substrate 200 is subsequently flipped upside down, and thefirst substrate 100 and the second substrate 200 are brought intophysical contact with each other as illustrated in FIG. 3 of the firstembodiment. Preferably, the first metal-containing material portions(170, 180) and the second metal-containing material portions (270, 280)are brought into contact with each other so that a surface of eachsecond semiconductor portion 280 contacts a surface of one of the firstsemiconductor portions 180 at an interface plane. Preferably, a surfaceof each of the first semiconductor portions 180 contacts a surface ofone of the second semiconductor portions 280 when the firstmetal-containing material portions (170, 180) and the secondmetal-containing material portions (270, 280) are brought into contactwith each other. The interface plane is the plane of the top surfaces ofthe first semiconductor portions 180 and first dielectric materialportions 190 as well as the plane of the top surfaces (now located atthe bottommost portion of the second substrate 200 after flipping upsidedown) of the second semiconductor portions 280 and the second dielectricmaterial portions 290. Subsequently, the same processing steps can beemployed to form metal semiconductor alloy portions 300 as illustratedin FIG. 4 and optionally to form at least two through-substrate viastructures 310 and at least one metal line 320 as illustrated in FIG. 5.

Referring to FIG. 9, a third exemplary structure according to a thirdembodiment of the present invention is derived from the first exemplarystructure of FIG. 1 by omitting the formation of a second semiconductorlayer 280L (See FIG. 1). The first metal layer 170L, the firstsemiconductor layer 180L, and the second metal layer 270L can be thesame as in the first embodiment.

Referring to FIG. 10, first metal-containing material portions and firstdielectric material portions 190 are formed in the same manner as in thefirst embodiment. Each of the first metal-containing material portionsis a first material stack of a first metal portion 170 and a firstsemiconductor portion 180. The first metal-containing material portions(170, 180) and the first dielectric material portions 190complimentarily fill the entirety of the layer between the top surfaceof the first planar dielectric layer 160 and the plane of the topsurfaces of the first semiconductor portions 180 and the firstdielectric material portions 190.

The second metal layer 270L is patterned to form trenches therein. A topsurface of the second planar dielectric layer 260 is exposed at thebottom of each trench in the stack of the second metal layer 270L andthe second semiconductor layer 280L. Preferably, the pattern of trenchesin the stack of the first metal layer 170L and the first semiconductorlayer 180L is a mirror image of the pattern of trenches in the secondmetal layer 270L. The remaining portions of the second metal layer 270Lform second metal-containing material portions, each of which is asecond metal portion 270. Each second metal-containing material portioncan be laterally spaced by the trenches on the second substrate 200.

A second dielectric material is deposited into the trenches among theremaining portions of the second metal layer 270L and planarized to formsecond dielectric material portions 290. The second dielectric materialabove the top surface of the second metal portions 270 is removed duringa planarization step so that remaining portions of the second metalportions 270 is exposed after the planarization step. The top surfacesof the second metal portions 270 and the top surfaces of the seconddielectric material portions 290 can be coplanar. The second metalportions 270 and the second dielectric material portions 290complimentarily fill the entirety of the layer between the top surfaceof the second planar dielectric layer 260 and the plane of the topsurfaces of the second metal portions 270 and the second dielectricmaterial portions 290.

The second substrate 200 is subsequently flipped upside down, and thefirst substrate 100 and the second substrate 200 are brought intophysical contact with each other. Preferably, the first metal-containingmaterial portions (170, 180) and the second metal-containing materialportions, which are second metal portions 270, are brought into contactwith each other so that a surface of each second metal portion 270contacts a surface of one of the first semiconductor portions 180 at aninterface plane. Preferably, a surface of each of the firstsemiconductor portions 180 contacts a surface of one of the second metalportions 270 when the first metal-containing material portions (170,180) and the second metal-containing material portions are brought intocontact with each other. The interface plane is the plane of the topsurfaces of the first semiconductor portions 180 and first dielectricmaterial portions 190 as well as the plane of the top surfaces (nowlocated at the bottommost portion of the second substrate 200 afterflipping upside down) of the second metal portions 270 and the seconddielectric material portions 290. Subsequently, the same processingsteps can be employed to form metal semiconductor alloy portions 300 asin the first embodiment. During formation of a metal semiconductoralloy, the semiconductor material in the first semiconductor portionsreacts with metallic materials of the first metal portions 170 and thesecond metal portions 270. Optionally, at least two through-substratevia structures 310 and at least one metal line 320 can be formed as inthe first embodiment.

Embodiments in which the first metal-containing material portions (170,180) or the second metal portions 270 are formed by methods of thesecond embodiment or methods derived from the second embodiment (forexample, by omission of formation of a second metal layer) can also beemployed.

Referring to FIG. 11, a fourth exemplary structure according to a fourthembodiment of the present invention includes a vertical stack of a firstplanar dielectric layer 160, a first metal layer 170L, and a firstsemiconductor layer 180L, which is formed on an exposed surface of afirst semiconductor substrate 201, i.e., on an opposite side of a firstinterconnect-level structure 151. The first semiconductor substrate 101is more proximal to the first semiconductor layer 180L than the firstinterconnect-level structure 151. Likewise, a vertical stack of a secondplanar dielectric layer 260, a second metal layer 270L, and a secondsemiconductor layer 280L is formed on an exposed surface of a secondsemiconductor substrate 202, i.e., on an opposite side of a secondinterconnect-level structure 251. The second semiconductor substrate 201is more proximal to the second semiconductor layer 280L than the secondinterconnect-level structure 251.

Referring to FIG. 12, first metal-containing material portions and firstdielectric material portions 190 are formed in the same manner as in thefirst embodiment. Each of the first metal-containing material portionsis a first material stack of a first metal portion 170 and a firstsemiconductor portion 180. The first metal-containing material portions(170, 180) and the first dielectric material portions 190complimentarily fill the entirety of the layer between the top surfaceof the first planar dielectric layer 160 and the plane of the topsurfaces of the first semiconductor portions 180 and the firstdielectric material portions 190.

Second metal-containing material portions and second dielectric materialportions 290 are formed in the same manner as in the second embodiment.Each of the second metal-containing material portions is a secondmaterial stack of a second metal portion 270 and a second semiconductorportion 280. The second metal-containing material portions (270, 280)and the second dielectric material portions 290 complimentarily fill theentirety of the layer between the top surface of the second planardielectric layer 260 and the plane of the top surfaces of the secondsemiconductor portions 280 and the second dielectric material portions290.

Referring to FIG. 13, the second substrate 200 is flipped upside down.Subsequently, the first substrate 100 and the second substrate 200 arebrought into physical contact with each other. Preferably, the firstmetal-containing material portions (170, 180) and the secondmetal-containing material portions (270, 280) are brought into contactwith each other so that a surface of each second semiconductor portion280 contacts a surface of one of the first semiconductor portions 180 atan interface plane. Preferably, a surface of each of the firstsemiconductor portions 180 contacts a surface of one of the secondsemiconductor portions 280 when the first metal-containing materialportions (170, 180) and the second metal-containing material portions(270, 280) are brought into contact with each other. The interface planeis the plane of the top surfaces of the first semiconductor portions 180and first dielectric material portions 190 as well as the plane of thetop surfaces (now located at the bottommost portion of the secondsubstrate 200 after flipping upside down) of the second semiconductorportions 280 and the second dielectric material portions 290.

Subsequently, metal semiconductor alloy portions 300 are formed acrossthe interface plane by conversion of materials of the firstmetal-containing material portions (170, 180) and the secondmetal-containing material portions (270, 280) into a metal semiconductoralloy employing the same methods as in the first embodiment. A bondedstructure including a vertical stack of the first substrate 100 and thesecond substrate 200 is thereby formed. The metal semiconductor alloyportions 300 provides adhesive force to the first substrate 100 and thesecond substrate 200, thereby providing bonding between the first andsecond substrates (100, 200). Further, the contact between the first andsecond dielectric material portions (190, 290) can induce diffusion ofmaterials across the interface plane to provide additional adhesiveforce in some cases.

The first semiconductor substrate 101 is more proximal to the interfaceplane than the first interconnect-level structure 151, and the secondsemiconductor substrate 201 is more proximal to the interface than thesecond interconnect-level structure 251. Optionally, at least twothrough-substrate via structures 310 that extend through the secondsubstrate 200 is formed as in the first embodiment At least one metalline 320 can be formed on the outer surface of the second substrate 200,i.e., the exposed surface of the second semiconductor substrate 201, asin the first embodiment. The at least one metal line 320 can directlycontact portions of the second conductive wiring structures 250. Athrough-substrate via structure 310 can contact one of the at least onemetal line and one of the first conductive wiring structures 150. Thethrough-substrate via structure 310 can pass through a stack of a firstdielectric material portion 190 and a second dielectric material portion290, or through a metal semiconductor alloy portion 300.

Embodiments in which the first metal-containing material portions (170,180) or the second metal portions 270 are formed by methods of thesecond embodiment, methods of the third embodiment, or a combinationthereof, can also be employed. Further, embodiments in which substratesare bonded front-to-back can also be employed. In one case, the firstsemiconductor substrate 101 is more proximal to the interface plane thanthe first interconnect-level structure 151, and the secondinterconnect-level structure 251 is more proximal to the interface thanthe second semiconductor substrate 201. Alternately, the firstinterconnect-level structure 151 is more proximal to the interface planethan the first semiconductor substrate 101, and the secondinterconnect-level structure 251 is more proximal to the interface thanthe second semiconductor substrate 201.

Referring to FIG. 14, a fifth exemplary structure according to a fifthembodiment of the present invention can be derived from any structure ofthe present invention by employing at least one of the metalsemiconductor alloy portions 300 as a part of an electrically conductivepath between the first substrate 100 and the second substrate 200. Atleast one of the first conductive wiring structures 150 and the secondconductive wiring structures 250 can contacts at least one of the metalsemiconductor alloy portions 300. In some cases, the first conductivewiring structures 150 and the second conductive wiring structures 250can contacts at least one of the metal semiconductor alloy portions 300.

Optionally, one of the at least two through-substrate via structures 310can contact one of the metal semiconductor alloy portions 300 to provideelectrically conductive path therebetween.

Referring to FIG. 15, a sixth exemplary structure according to a sixthembodiment of the present invention can be derived from any structure ofthe present invention by employing at least one through-substrate viastructures 310 as a part of an electrically conductive path. Athrough-substrate via structures 310 can contact one of the metalsemiconductor alloy portions 300 to be employed as a part of anelectrically conductive path.

Referring to FIG. 16, a seventh exemplary structure according to aseventh embodiment of the present invention can be derived from anystructure of the present invention by employing a through-substrate viastructure 310 that contacts one of the second conductive wiringstructures and another through-substrate via structure 310 that contactsone of the metal semiconductor alloy portions 300.

Referring to FIG. 17, an eighth exemplary structure according to aneighth embodiment of the present invention can be derived from any ofthe first through seventh exemplary structures of the present inventionby forming a layer complimentarily filled with third dielectric materialportions 390 and third metal-containing material portions. Each of thethird metal-containing material portions can be a third material stackof a third metal portion 370 and a third semiconductor portion 380.

Referring to FIG. 18, a third substrate 400 is provided, which caninclude a third semiconductor substrate 401 and a thirdinterconnect-level structure 451. The third semiconductor substrate 401can includes a third semiconductor layer 410. At least one thirdsemiconductor device 420 can be present on the third semiconductor layer410. The at least one third semiconductor device 420 can be any devicethat the at least one first semiconductor device 120 or the at least onesecond semiconductor device 220 can be. The third semiconductor layer410 includes a semiconductor material, which can be any material thatthe materials of the first and second semiconductor layers (110, 210)can be.

The third interconnect level structure 451 includes at least one thirddielectric material layer 440 and third conductive wiring structures 450embedded therein. The third conductive wiring structures 450 can includethird conductive via structures 452 and third conductive line structures454. The at least one first dielectric material layer 440 can includeany dielectric material that the at least one first dielectric materiallayer 140 and the at least one second dielectric material layer 240 caninclude. The third conductive wiring structures 450 embedded in the atleast one third dielectric material layer 440 provide electricalconnection to the at least one third semiconductor device 420. The atleast one third dielectric material layer 440 can include a plurality ofdielectric material layers having different compositions.

Fourth metal-containing material portions and fourth dielectric materialportions 490 are formed employing any of the methods in the firstthrough third embodiments. Each of the fourth metal-containing materialportions can be a fourth material stack of a fourth metal portion 470and a fourth semiconductor portion 480. Alternately, each of the fourthmetal-containing material portions can consist of a fourth metal portion470. Embodiments are also contemplated in which third metal-containingmaterial portions consist of third metal portions 370 and each of thefourth metal-containing material portions is a fourth material stack ofa fourth metal portion 470 and a fourth semiconductor portion 480. Thefourth metal-containing material portions and the fourth dielectricmaterial portions 490 complimentarily fill the entirety of a materiallayer (470, 480, 490).

The third substrate 400 is flipped upside down, and the assembly of thefirst substrate 100 and the second substrate 200 are brought intophysical contact with the third substrate 400. Preferably, the thirdmetal-containing material portions (370, 380) and the fourthmetal-containing material portions (470, 480) are brought into contactwith each other so that a surface of each fourth semiconductor portion480 contacts a surface of one of the third semiconductor portions 380 atan interface plane. Preferably, a surface of each of the thirdsemiconductor portions 380 contacts a surface of one of the fourthsemiconductor portions 480 when the third metal-containing materialportions (370, 380) and the fourth metal-containing material portions(470, 480) are brought into contact with each other.

Subsequently, the same processing steps can be employed to form secondmetal semiconductor alloy portions 500 as in the first embodiment.During formation of another metal semiconductor alloy, the semiconductormaterials in the third and fourth semiconductor portions (380, 480)react with metallic materials of the third and fourth metal portions(370, 470). Optionally, at least two through-substrate via structures510 and at least one metal line 520 can be formed.

While the present invention has been particularly shown and describedwith respect to preferred embodiments thereof, it will be understood bythose skilled in the art that the foregoing and other changes in formsand details can be made without departing from the spirit and scope ofthe present invention. It is therefore intended that the presentinvention not be limited to the exact forms and details described andillustrated, but fall within the scope of the appended claims.

What is claimed is:
 1. A bonded structure comprising a vertical stackcontaining, from bottom to top, at least: a first semiconductorsubstrate; a first interconnect-level structure; a first planardielectric layer; a layer complementarily filled with metalsemiconductor alloy portions and vertical stacks of dielectric materialportions, each of said vertical stacks of dielectric material portionsincluding a first dielectric material portion and a second dielectricmaterial portion that contact each other within a same interface planethat is common across all of said vertical stacks; a second planardielectric layer; a second interconnect-level structure; and a secondsemiconductor substrate, wherein an entire top surface of one of saidmetal semiconductor alloy portions is in physical contact with adielectric surface of said second planar dielectric layer, an entirebottom surface of said one of said metal semiconductor alloy portions isin physical contact with a dielectric surface of said first planardielectric layer, and entire sidewall surfaces of said one of said metalsemiconductor alloy portions are in physical contact with surfaces ofsaid vertical stacks of dielectric material portions.
 2. The bondedstructure of claim 1, wherein said metal semiconductor alloy portionsare comprised of an alloy of at least one metal selected from transitionmetals, Lanthanides, and Actinides, and at least one semiconductorelement selected from Si and Ge.
 3. The bonded structure of claim 2,wherein said metal semiconductor alloy portions are comprised of a metalsilicide, a metal germanide, or a metal germanosilicide.
 4. The bondedstructure of claim 3, wherein said at least one metal is nickel or ametallic alloy including at least 30% of nickel in atomic percentage. 5.The bonded structure of claim 1, wherein an entire interface betweensaid first planar dielectric layer and said complementarily filled layeris planar.
 6. The bonded structure of claim 5, wherein an entireinterface between said second planar dielectric layer and saidcomplementarily filled layer is planar.
 7. The bonded structure of claim1, wherein said first interconnect-level structure comprises firstconductive wiring structures and at least one first dielectric materiallayer, and said second interconnect-level structure comprises secondconductive wiring structures and at least one second dielectric materiallayer.
 8. The bonded structure of claim 7, wherein said firstinterconnect-level structure is more proximal to said same interfaceplane than said first semiconductor substrate, and said secondinterconnect-level structure is more proximal to said same interfaceplane than said second semiconductor substrate.
 9. The bonded structureof claim 7, wherein at least one of said first conductive wiringstructures and said second conductive wiring structures contacts a topsurface or a bottom surface of another of said metal semiconductor alloyportions.
 10. The bonded structure of claim 7, further comprising: atleast two through-substrate via structures that extend through saidsecond semiconductor substrate and said second interconnect-levelstructure; and at least one metal line contacting said at least twothrough-substrate via structures.
 11. The bonded structure of claim 10,wherein one of said at least two through-substrate via structurescontacts one of said second conductive wiring structures.
 12. The bondedstructure of claim 10, wherein one of said at least twothrough-substrate via structures contacts one of said metalsemiconductor alloy portions.
 13. The bonded structure of claim 10,wherein one of said at least two through-substrate via structurescontacts one of said first conductive wiring structures.
 14. The bondedstructure of claim 1, further comprising a third substrate verticallycontacting one of said first and second substrates, wherein said secondsubstrate further includes third dielectric material portions and saidthird substrate includes fourth dielectric material portions, each ofsaid fourth dielectric material portions contacts a surface of one ofsaid third dielectric material portions at a second interface planebetween said second and third substrates, said third dielectric materialportions and said fourth dielectric material portions laterally contactsecond metal semiconductor alloy portions, and each of said second metalsemiconductor alloy portions extends across said second interface intosaid second substrate and said third substrate.
 15. The bonded structureof claim 1, wherein said metal semiconductor alloy portions include atleast one metal semiconductor alloy portion that is not in directcontact with any conductive structure embedded in at least one of saidfirst interconnect-level structure, said first planar dielectric layer,said second planar dielectric layer, and said second interconnect-levelstructure.
 16. The bonded structure of claim 1, wherein each of saidmetal semiconductor alloy portions is not in direct contact with anyconductive structure embedded in at least one of said firstinterconnect-level structure, said first planar dielectric layer, saidsecond planar dielectric layer, and said second interconnect-levelstructure.